Headers are known and widely used for harvesting crop material with an agricultural harvester. Sickle knives have been used to cut plants, including, but not limited to, hay, grasses, small grains and the like, for many years. The knives typically include an elongate metal sickle bar, with a plurality of knife sections attached along the lengths thereof. The sickle bar normally slides along the header frame, which has guards bolted to the header frame. The sickle bar and header frame are oriented to as to extend sideward along a forward edge portion of the header of the agricultural combine. The sickle bar with the knife sections move reciprocally between the guards so that the leading edges of the knife sections cross over the guards or through slots in the guards. This produces a sheering action which severs plant stems and stalks or other material captured between the knives and the guards. The sickle bar is typically reciprocally actuated by an actuator, which can include, but is not limited to, an eccentric shaft or a rotating hub, a wobble drive, or a similar well known commercially available device. The sickle bar may weigh as much as 30 kilograms or more, and is typically accelerated and decelerated two times per cycle as a result of the reciprocal movement. Thereby, a typical speed for the sickle bar is up to about 16 Hz or cycles per second. The back and forward motion at a high cycle per second generates high acceleration values and high deceleration values that in turn generate high forces on structural components.
US 2005/0109005 aims to decrease the forces on structural components and describes a sickle bar having two segments each equal to one half the sideward extent of the header, which are driven by oscillating devices that are timed such that the sickle bars are travelling in opposite directions. Thereby, US 2005/0109005 describes a mechanism that provides this opposite travel direction in an efficient manner. Due to the sickle bar having two segments travelling in opposite directions, acceleration values as well as forces on the structural components are decreased.
It is an object of the present invention to further decrease forces on structural components of the header that result from the acceleration and deceleration of the elongate sickle knife.